The received signal is the sum of the direct and ground-reflected signals and since they travel at different distances they have different time delays. If the transmitted signal is s(t) then the received signal is x t s t t s t t ( ) ( ) ( ) = − + − 1 2 The amount of delay (in seconds) can be computed for both propagation paths, using the fact that the time delay is the distance divided by the speed of light (3 10 × 8 m/sec). Determine t1 and t2 as a function of d1.

The mass flow rate of the fluid remains constant in all steady flow process. a)- true b)- false

The sum of the normal stresses does not change as the stress state rotates through an angle. a)-trune b)- false

Afoot bridge is made as a simple deck, 4 m long, with a cross section 2 m (wide) and 20 cm thick, and made of wood. the deck is supported at the two ends. the maximum load allowable on the bridge is 10 tons, provided it is uniformly distributed on the deck. to sense this load, a strain gauge is placed at the center of the bridge and its resistance is monitored. if the sensor has a nominal resistance of 350 s2 and a gauge factor of 3.6, what is the reading of the strain gauge at maximum load? the modulus of elasticity for the wood used in the construction is 10 gpa.